This invention relates to chutes for use in inspection and sorting apparatus, particularly to such apparatus in which products are fed to a chute which delivers it to a sorting or inspection station. Sorting apparatus of this type is described in U.S. Pat. Nos. 4,513,868; 4,630,736; and 5,628,411, the disclosures whereof are hereby incorporated by reference. Inspection apparatus can use similar techniques but for the purpose of gathering data, rather than ejecting unacceptable pieces from the product stream.
For some products, grooved or channelled chutes are used to orient and position the product pieces when they leave the lower end of the chute. This facilitates the sorting or inspection process, and in sorting apparatus can help to ensure that devices and mechanisms used to eject pieces from the product stream operate only on the properly selected pieces.
In the sorting or inspection station in apparatus of the kind to which the invention relates, product is normally delivered from a supply hopper onto a vibratory feeder which discharges it to form a stream on a chute for delivery to a sorting or inspection station. At that station the apparatus will typically use an optical system to differentiate between product pieces of different quality, and ideally each product piece in the product stream is separate from all adjacent pieces so that individuals can be readily identified and as appropriate, ejected. At the same time it is of course desirable to have as many pieces as possible in the product stream. As the product flows off the vibrator it is moving relatively slowly. In some known apparatus, where the product feeds straight off a feeder tray onto a channelled chute, the product is fed straight into the channels. If two or more grains enter a channel at the same time they will travel side by side in the channel, a little slower than individual grains, that will catch up with them and then form bunches. Once in the channel there is a tendency for these bunches of product to travel at the same velocity and not separate out on the chute, thus passing the inspection station as bunches rather than individual spaced product pieces. This reduces the efficiency of the inspection and in sorting apparatus can cause more than one grain to be ejected if a defect is detected. To avoid this it is necessary to limit the rate of flow of product into the chute and the capacity of the apparatus is reduced. This problem is addressed in International Patent Publication No: WO 2006/010 873, the disclosure whereof is hereby incorporated by reference. That publication discloses a chute having a first smooth section and a second grooved section receiving product from the first section and from which the product is eventually discharged.